(function() {
  "use strict";

  var Pos = CodeMirror.Pos;
  function cmp(a, b) { return a.line - b.line || a.ch - b.ch; }

  var nameStartChar = "A-Z_a-z\\u00C0-\\u00D6\\u00D8-\\u00F6\\u00F8-\\u02FF\\u0370-\\u037D\\u037F-\\u1FFF\\u200C-\\u200D\\u2070-\\u218F\\u2C00-\\u2FEF\\u3001-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFFD";
  var nameChar = nameStartChar + "\-\:\.0-9\\u00B7\\u0300-\\u036F\\u203F-\\u2040";
  var xmlTagStart = new RegExp("<(/?)([" + nameStartChar + "][" + nameChar + "]*)", "g");

  function Iter(cm, line, ch, range) {
    this.line = line; this.ch = ch;
    this.cm = cm; this.text = cm.getLine(line);
    this.min = range ? range.from : cm.firstLine();
    this.max = range ? range.to - 1 : cm.lastLine();
  }

  function tagAt(iter, ch) {
    var type = iter.cm.getTokenTypeAt(Pos(iter.line, ch));
    return type && /\btag\b/.test(type);
  }

  function nextLine(iter) {
    if (iter.line >= iter.max) return;
    iter.ch = 0;
    iter.text = iter.cm.getLine(++iter.line);
    return true;
  }
  function prevLine(iter) {
    if (iter.line <= iter.min) return;
    iter.text = iter.cm.getLine(--iter.line);
    iter.ch = iter.text.length;
    return true;
  }

  function toTagEnd(iter) {
    for (;;) {
      var gt = iter.text.indexOf(">", iter.ch);
      if (gt == -1) { if (nextLine(iter)) continue; else return; }
      if (!tagAt(iter, gt + 1)) { iter.ch = gt + 1; continue; }
      var lastSlash = iter.text.lastIndexOf("/", gt);
      var selfClose = lastSlash > -1 && !/\S/.test(iter.text.slice(lastSlash + 1, gt));
      iter.ch = gt + 1;
      return selfClose ? "selfClose" : "regular";
    }
  }
  function toTagStart(iter) {
    for (;;) {
      var lt = iter.ch ? iter.text.lastIndexOf("<", iter.ch - 1) : -1;
      if (lt == -1) { if (prevLine(iter)) continue; else return; }
      if (!tagAt(iter, lt + 1)) { iter.ch = lt; continue; }
      xmlTagStart.lastIndex = lt;
      iter.ch = lt;
      var match = xmlTagStart.exec(iter.text);
      if (match && match.index == lt) return match;
    }
  }

  function toNextTag(iter) {
    for (;;) {
      xmlTagStart.lastIndex = iter.ch;
      var found = xmlTagStart.exec(iter.text);
      if (!found) { if (nextLine(iter)) continue; else return; }
      if (!tagAt(iter, found.index + 1)) { iter.ch = found.index + 1; continue; }
      iter.ch = found.index + found[0].length;
      return found;
    }
  }
  function toPrevTag(iter) {
    for (;;) {
      var gt = iter.ch ? iter.text.lastIndexOf(">", iter.ch - 1) : -1;
      if (gt == -1) { if (prevLine(iter)) continue; else return; }
      if (!tagAt(iter, gt + 1)) { iter.ch = gt; continue; }
      var lastSlash = iter.text.lastIndexOf("/", gt);
      var selfClose = lastSlash > -1 && !/\S/.test(iter.text.slice(lastSlash + 1, gt));
      iter.ch = gt + 1;
      return selfClose ? "selfClose" : "regular";
    }
  }

  function findMatchingClose(iter, tag) {
    var stack = [];
    for (;;) {
      var next = toNextTag(iter), end, startLine = iter.line, startCh = iter.ch - (next ? next[0].length : 0);
      if (!next || !(end = toTagEnd(iter))) return;
      if (end == "selfClose") continue;
      if (next[1]) { // closing tag
        for (var i = stack.length - 1; i >= 0; --i) if (stack[i] == next[2]) {
          stack.length = i;
          break;
        }
        if (i < 0 && (!tag || tag == next[2])) return {
          tag: next[2],
          from: Pos(startLine, startCh),
          to: Pos(iter.line, iter.ch)
        };
      } else { // opening tag
        stack.push(next[2]);
      }
    }
  }
  function findMatchingOpen(iter, tag) {
    var stack = [];
    for (;;) {
      var prev = toPrevTag(iter);
      if (!prev) return;
      if (prev == "selfClose") { toTagStart(iter); continue; }
      var endLine = iter.line, endCh = iter.ch;
      var start = toTagStart(iter);
      if (!start) return;
      if (start[1]) { // closing tag
        stack.push(start[2]);
      } else { // opening tag
        for (var i = stack.length - 1; i >= 0; --i) if (stack[i] == start[2]) {
          stack.length = i;
          break;
        }
        if (i < 0 && (!tag || tag == start[2])) return {
          tag: start[2],
          from: Pos(iter.line, iter.ch),
          to: Pos(endLine, endCh)
        };
      }
    }
  }

  CodeMirror.registerHelper("fold", "xml", function(cm, start) {
    var iter = new Iter(cm, start.line, 0);
    for (;;) {
      var openTag = toNextTag(iter), end;
      if (!openTag || iter.line != start.line || !(end = toTagEnd(iter))) return;
      if (!openTag[1] && end != "selfClose") {
        var start = Pos(iter.line, iter.ch);
        var close = findMatchingClose(iter, openTag[2]);
        return close && {from: start, to: close.from};
      }
    }
  });
  CodeMirror.tagRangeFinder = CodeMirror.fold.xml; // deprecated

  CodeMirror.findMatchingTag = function(cm, pos, range) {
    var iter = new Iter(cm, pos.line, pos.ch, range);
    if (iter.text.indexOf(">") == -1 && iter.text.indexOf("<") == -1) return;
    var end = toTagEnd(iter), to = end && Pos(iter.line, iter.ch);
    var start = end && toTagStart(iter);
    if (!end || end == "selfClose" || !start || cmp(iter, pos) > 0) return;
    var here = {from: Pos(iter.line, iter.ch), to: to, tag: start[2]};

    if (start[1]) { // closing tag
      return {open: findMatchingOpen(iter, start[2]), close: here, at: "close"};
    } else { // opening tag
      iter = new Iter(cm, to.line, to.ch, range);
      return {open: here, close: findMatchingClose(iter, start[2]), at: "open"};
    }
  };

  CodeMirror.findEnclosingTag = function(cm, pos, range) {
    var iter = new Iter(cm, pos.line, pos.ch, range);
    for (;;) {
      var open = findMatchingOpen(iter);
      if (!open) break;
      var forward = new Iter(cm, pos.line, pos.ch, range);
      var close = findMatchingClose(forward, open.tag);
      if (close) return {open: open, close: close};
    }
  };
})();
